Method and apparatus for the drying, concentration or crystallization of liquid materials



May 10, 1955 METHOD AND APPARATUS FOR THE DRYING.

OR CRYSTALLIZATION OF LIQUID MATERIALS Filed April 18, 1949 J E N INVENTOR.

. YROP BY WM, MK! M ATTORNEYS United States Patent 2 2,707,990 METHOD AND APPARATUS FOR THE DRYING,

CONCENTRATION (BR CRYSTALLIZATION 0F LIQUID MATERIALS Johan Ernst Nyrop, Hellerup, near Copenhagen, Denmark, assignor, by mesne assignments, to Niro Corporation, New York, N. Y.

is brought into contact with a flow of a drying medium which is supplied centrally in the chamber under the atomization zone and which together with the atomized material moves down through the chamber and is removed at the lowest part of the latter.

In order to avoid the formation of vortices, whereby some of the atomized material may be led towards hot surfaces in the apparatus and thereby be more or less damaged, it has been proposed to mount stationary guide surfaces in line with the mouth of the central supply pipe which causes the drying medium flowing into the chamber to be distributed diffusely, i. e. distributed in such a way that in any vertical diametrical cross section, the drying medium will flow from the supply opening in a substantially uniform distribution towardsthe free part of the chamber ceiling as well as towards the parts of the side wall of the chamber situated above the point of supply for the drying medium. Modifications are known in which the drying medium is moved in a rotating flow upwardly towards said guide surfaces, but for attaining said effect it has been regarded as being of no consequence whether the medium was circulating or not.

I have discovered, however, that the stationary guide member will cause the formation of vortices whether the exhaust of the medium is circulating or not, whereby the atomized material is led towards the guide member where it may be deposited and be damaged.

An object of the present invention is to provide a method for drying, concentrating or crystallizing by atomization in such a manner that an improved diffused distribution of the drying medium is obtained.

A further object of the present invention is to provide a method for drying by atomization in such a manner that the risk of deposition of the atomized particles on hot surfaces is greatly reduced.

A further object of the present invention is to obtain improved devices for the atomization of liquids by which devices the above mentioned advantages can be obtained.

An important feature of the invention consists of the arrangement wherein the drying medium is supplied through a centrally disposed supply pipe and circulated so that the velocity of rotation at the periphery of the mouth is greater than the velocity of advance.

By this feature a completely ditfused distribution of the drying medium is obtained and the risk of the formation of vortices is substantially eliminated.

The rotational circulation may be obtained in various manners e. g. by means of vanes at the mouth of the supply tube.

Such vanes may be stationary and in this case they should be disposed completely within the tube, so that no stationary part is present in the space between the mouth of the tube and the atomizer. The vanes may also be rotatable and in this case they may extend outside the mouth into said space.

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velocity of rotation is at least /2 times that of the advance.

The guide vanes may be stationary, and the resulting vortices formed by passing the drying fluid over the vanes mounted in the supply pipe provide a self-cleaning action within the pipe proper where there are no atomized particles and prevent the particles from being led towards and from sticking to the stationary guide vanes.

It is, however, contemplated by the invention that the guide vanes be rotatable. The rotation of the guide vanes may be brought about in any suitable manner, but in ac.- cordance with the invention it is advantageous that they be mounted and constructed to be put into rotation by the drying medium. This may be achieved by suitable shaping of the guide vanes and by using the drying medium as a propelling fiuid such as is used for the operation for driving turbine.

The rotational movement of the drying fluid and the diffusing action in the construction may be further increased in accordance with the invention at the mouth of the pipe by providing a substantially conically expanded portion therein and in which the guide vanes are mounted on a boss which forms a substantially conical guide surface, the point of which faces the mouth of the pipe.

in the following the invention is further explained with reference to the drawing, where Fig. 1 diagrammatically shows a accordance with the invention,

Fig. 2 a corresponding detail of a modified embodiment of the apparatus, where the rotation of the vanes is brought about by means of the drying medium with an air turbine as an intermediate link,

Fig. 3 is a third embodiment where the rotation of the vanes is the result of the axial flow of the drying medium, and

Fig. 4 is an embodiment with stationary guide vanes.

Fig. 1 shows an embodiment of a drying apparatus for drying and crystallizing of solutions or liquid molecular dispersions by atomizing the liquid.

The apparatus consists of a drying chamber 22 with an atomizer 21. A drying medium such as hot air, steam, combustion products or other inert gas, is led into the chamber 22 through a lead-in pipe 32. At the mouth 35 of the pipe 32 are disposed suitably shaped deflecting vanes 35, as further explained below.

The drying medium is removed from the apparatus through pipe 26 and the dried product which. settles to the bottom of the lower 30 of the chamber 22, can be removed through a removable closure 23.

To prevent the dried product from being sucked out by the exiting drying medium taken off. through the pipe 26 a conical screen 31 is disposed beneath the mouth of this pipe.

A secondary part of the drying medium may be taken out through the pipe 28 to avoid the formation of vortices in the chamber.

it should be understood that the invention is by no way limited to the application of a drying apparatus of the embodiment shown in Fig. l, as any other appropriate form for such apparatus may be applied. This apparatus is only shown for the better comprehension of the application of the inventional features.

in the embodiment shown in Fig. 2, as well as in those shown in Figs. 3 and 4, the supply pipe 1 is shaped so as to have a constant diameter. In Fig. 2, the vanes 3 are driven through a gearing 6 by a gas turbine 7 which is placed in the interior of the supply pipe in such a way that the drying medium flows through the turbine and thereby drives the vanes.

In the embodiment shown in Fig. 3, the vanes are shaped in such a way that they are made to rotate by drying apparatus in the flowing medium proper and thereby give the latter the necessary angular or rotary velocity.

The embodiment shown in Fig. 4 diifers from that shown in Fig. 3 in that the guide vanes are stationary.

The constructions of the vanes indicated on the drawing should only be regarded as diagrammatical, it being possible to apply any suitable shape, and it will be possible for any expert to select such a shape that the circulation velocity indicated by the invention is attained for the drying medium.

I claim:

1. A method for drying a solid dispersed in a liquid, comprising atomizing said liquid in the upper part of a drying chamber, contacting the atomized liquid from below with a directed stream of drying fluid centrally supplied from the mouth of a supply pipe to said chamber, rotating said stream of drying fluid about the axis of said pipe, by providing deflecting guide vanes within said pipe near the mouth thereof, to impart to said rotating drying fluid a mean tangential velocity component at the periphery of the pipe which is greater than the axial velocity component of said rotating fluid at the mouth of said pipe, the so-diitused fluid stream passing unobstructcdiy from said vanes into said chamber and into di' rect contact with the atomized liquid to produce dried particles which fall to the bottom of the drying chamber, and removing the drying fluid and the dried particles from the bottom of the drying chamber.

2. An apparatus for drying a solid dispersed in a liquid comprising a drying chamber, an atomizer in the upper part of said chamber to atomize said liquid, a supply pipe mounted centrally in said chamber below said atomizer to direct a stream of a drying fluid into unobstructed contact with the atomized liquid, deflecting guide vanes mounted within said pipe at the mouth thereof to rotate said stream of drying fluid and impart a mean tangential velocity component of said rotated stream of drying fluid at the periphery of said pipe which is greater than the axial velocity component of said rotated stream, whereby the action of: the so-ditfused drying fluid produces dried particles which fall to the bottom of the drying chamber, and discharging means at the bottom of said drying chamber for removing the drying fluid.

3. An apparatus for drying a solid dispersed in a liquid comprising a drying chamber, an atomizer in the upper part of said chamber to atomize said liquid, a supply pipe mounted centrally in said chamber below said atomizer to direct a stream of a drying fluid int'o unobstructed contact with the atomized liquid, deflecting guide vanes mounted within said pipe at the mouth thereof to rotate said stream of drying fluid and impart a mean tangential velocity component of said rotated stream of drying fluid at the periphery of said pipe which is greater than the axial velocity component of said rotated stream, said vanes being fixed within said pipe and extending to the mouth of said pipe, whereby the action of the so-diifused drying fiuid produces dried particles which fall to the bottom of the drying chamber, and discharging means at the bottom of said drying chamber for removing the drying fluid.

4. An apparatus for drying a solid dispersed in a liquid comprising a drying chamber, an atomizer in the upper part of said chamber to atomize said liquid, a supply pipe mounted centrally in said chamber below said atomizer to direct a stream of a drying fluid into unobstructed contact with the atomized liquid, deflecting guide vanes mounted Within said pipe at the mouth thereof to rotate said stream of drying fluid and impart a mean tangential velocity component of said rotated stream of drying fluid at the periphery of said pipe which is greater than the axial velocity component of said rotated stream, said vanes being rotatable and caused to rotate by the drying fluid passing through the pipe, whereby the action of the sodiffused drying fluid produces dried particles which fall to the bottom of the drying chamber, and discharging means at the bottom of said drying chamber for removing the drying fluid.

References Cited in the file of this patent UNITED STATES PATENTS 1,501,952 Kranse July 22, 1924 1,871,737 Richards Aug. 16, 1932 2,559,989 Nyrop July 10, 1951 FOREIGN PATENTS 544,215 France June 16, 1922 357,205 Germany Aug. 19, 1922 393,467 Germany Apr. 3, 1924 394,912 Great Britain July 6, 1933 478,925 Great Britain Jan. 27, 1938 58,008 Holland Aug. 15, 1946 

1. A METHOD FOR DRYING A SOLID DISPERSED IN A LIQUID, COMPRISING ATOMIZING SAID LIQUID IN THE UPPER PART OF A DRYING CHAMBER, CONTACTING THE ATOMIZED LIQUID FROM BELOW WITH A DIRECTED STREAM OF DRYING FLUID CENTRALLY SUPPLIED FROM THE MONTH OF A SUPPLY PIPE TO SAID CHAMBER, ROTATING SAID STREAM OF DRYING FLUID ABOUT THE AXIS OF SAID PIPE, BY PROVIDING DEFLECTING GUIDE VANES WITHIN SAID PIPE NEAR THE MONTH THEREOF, TO IMPACT TO SAID ROTATING DRYING FLUID A MEAN TANGENTIAL VELOCITY PERIPHERY OF THE PIPE WHICH IS GREATER THAN THE AXIAL VELOCITY COMPONENT OF SAID ROTATING FLUID AT THE MONTH OF SAID PIPE, THE SO-DIFFUSED FLUID STREAM PASSING UNOBSTRUCTEDLY FROM SAID VANES INTO SAID CHAMBER AND INTO DIRECT CONTACT WITH THE ATOMIZED LIQUID TO PRODUCE DRIED PARTICLES WHICH FALL TO DRYING FLUID AND THE DRIED PARTICLES FROM THE BOTTOM OF THE DRYING CHAMBER. 